Flood-induced mobilization of industrial contaminants in the United States: mechanisms, exposure pathways, and implications for water and health policy

Flooding is an increasingly important driver of water quality degradation and human exposure to industrial contaminants under changing climate conditions. Floodwaters mobilize contaminants stored in sediments, soils, industrial facilities, and aging infrastructure, altering transport pathways, geochemical behavior, and exposure risks across aquatic and terrestrial environments. This review synthesizes current understanding of flood-induced contaminant mobilization in the United States and evaluates implications for water quality, human health, and environmental policy. A structured, evidence-informed review of peer-reviewed literature and governmental reports published between 1990 and 2026 was conducted, integrating findings across hydrodynamic forcing, sediment transport, geochemical transformation, infrastructure failure, and human exposure pathways. The analysis indicates that floods mobilize contaminants through multiple interacting mechanisms, including sediment resuspension, erosion of contaminated soils, geochemical transformations, and releases from damaged infrastructure. Distinct transport behaviors were identified among contaminant classes, with metals and persistent organic pollutants transported predominantly through sediment-associated pathways, while more mobile compounds such as per- and polyfluoroalkyl substances (PFAS) are often transported in dissolved phases. Organic industrial chemicals exhibit mixed dissolved and particulate transport pathways, while flood-induced changes in redox conditions, salinity, and organic matter availability strongly influence contaminant mobility, persistence, and bioavailability. Human exposure occurs through contaminated drinking water, direct floodwater contact, aerosol inhalation, contaminated soils and sediments, and food-chain transfer. The magnitude and persistence of contamination vary substantially with flood characteristics, sediment properties, contaminant type, and geochemical conditions. Although consistent evidence supports the importance of sediment-associated transport and infrastructure-mediated releases, significant uncertainties remain regarding post-flood remobilization, contaminant mixtures, and long-term health risks. These findings highlight the need for improved event-based monitoring, integrated modeling frameworks, and risk-informed policy strategies to better manage water quality and protect public health in increasingly flood-prone environments.”